The Clinical Core occupies a central role to the accomplishments of the Program Project and Individual Clinical Projects. Specifically, this Core will: 1) Provide long-term follow-up of previously recruited patient populations, 2) Recruit (for the Individual Projects) and provide long-term follow-up of new "Special Populations" of Alzheimer's Disease (AD) patients, including minority AD patients (American Black), AD patients with a concurrent depression, and AD patients with desired SPECT scans (normal, unilateral/focal abnormalities, "classic" changes), 3) Assist in the acquisition of tissue for the Tissue Procurement Immunocytochemistry Core, and 4) Provide data management and biostatistical services.